1. Field of the Invention
The present invention relates to a method of measuring the dielectric constant of powder, and more particularly, it relates to a method of measuring the dielectric constant of powder by measuring an apparent dielectric constant of a composite system of the powder and a liquid medium and thereafter finding the dielectric constant of the powder with application of the logarithmic mixing rule or the Lichtone-Rother equation.
2. Description of the Background Art
While various dielectrics are employed in the field of electronic components, for example, it is necessary to measure the dielectric constant of the dielectric that is employed, in order to design an electronic component. An inorganic dielectric such as ceramic, for example, which is applied to an electronic component is generally prepared in a state of powder. In evaluation of the dielectric constant of an inorganic dielectric such as ceramic, therefore, ceramic powder is generally molded with a binder and the compact thereby obtained is then fired and provided on its surface with a silver electrode, to be subjected to the measurement of the dielectric constant.
However, the aforementioned method of measuring the dielectric constant is rather inferior in efficiency. In order to solve this problem, there has been proposed the following method of finding the dielectric constant of powder as such.
A container provided with a pair of electrodes, which are opposed to each other at a constant distance, is prepared so that powder to be subjected to measurement of its dielectric constant .epsilon..sub.1 is introduced therein with a liquid medium having a known dielectric constant. In this state, a voltage is applied across the pair of electrodes, to measure an apparent dielectric constant .epsilon. of a composite system of the powder and the liquid medium. Then, the dielectric constant .epsilon..sub.1 of the powder is found by an equation, such as the logarithmic mixing rule or the Lichtone-Rother equation, for calculating the dielectric constant of a mixed material. In more concrete terms, the dielectric constant .epsilon..sub.1 of the powder is calculated by the logarithmic mixing rule: EQU log .epsilon.=v.sub.1 log .epsilon..sub.1 +v.sub.2 log .epsilon..sub.2
or the Lichtone-Rother equation: EQU .epsilon..sup.k =v.sub.1 .epsilon..sub.1.sup.k +v.sub.2 .epsilon..sub.2.sup.k (-1.ltoreq.k.ltoreq.1)
where .epsilon..sub.1 represents the dielectric constant of the powder, .epsilon..sub.2 represents the dielectric constant of the liquid medium, v.sub.1 represents the volume ratio of the powder, and v.sub.2 represents the volume ratio of the liquid medium.
However, neither the logarithmic mixing rule nor the Lichtone-Rother equation has a theoretical ground, although the same is convenient for approximately calculating the dielectric constant of a mixed material. Therefore, the dielectric constant value of a composite system which is calculated according to the aforementioned logarithmic mixing rule or Lichtone-Rother equation may disagree with a measured value. This means that the dielectric constant value of the powder measured by the above mentioned is not reliable.